Advancing the lighted nock design by which all others are judged. Lighted nocks take the simplicity and reliability of the world's most dependable and user-friendly lighted nock to an entirely new level. Thanks to the external on/off switch the process of turning an ultra-bright, string activated Nockturnal lighted nock off has never been easier. Just slide the switch and the nock turns off. With 20+ hours of long-lasting battery life and a durable design these nocks are built to last and perform like none other. Constructed of an ultra-strong, impact resistant, polycarbonate casing that protects the super-bright LED lights Shift nocks deliver on what users have come to expect from Nockturnal lighted nocks. The patented, string-activated, piston-driven contact linear switch triggers the nock to illuminate immediately when the string is released and can be quickly turned off with the external switch, a true evolution in the world's most reliable lighted nock system. Features: Super Strong Clear Polycarbonate Construction Waterproof and Shock Proof Easy on/off light system Specifications: Fits X, H, S, and GT Arrows H (white bushing) = Fits smaller diameter carbon .233 ID shafts GT (black bushing) = Fits smaller diameter carbon .246 ID shafts S (gray bushing) = Fits standard carbon .244 ID shafts X (no bushing) = Fits smaller diameter carbon .204 ID shafts Each nock in this package weighs approximately 25 grains Delivers more than 20 hours of lithium-powered battery life Quantity: 3-pack